Hi, since the Tails ISO grew from ~900MB to ~1.1GB, we see this warning when running isohybrid on it: isohybrid: Warning: more than 1024 cylinders: 1045 isohybrid: Not all BIOSes will be able to boot this device I guess that's fully expected. And, as expected, we get boot failure reports from users. So, my question is: is there a "known optimal" combination of isohybrid options that makes the resulting hybrid'd ISO boot on as much hardware as possible? Notes: * I've sent a call for testing to the Tails community in order to gather experimental results in this area, but it might be that someone in here already knows better. * We currently use "--entry 4 --type 0x1c", for historical reasons; that doesn't impact whether the warning is displayed; however, it probably impacts on what hardware the USB stick boots or not. Cheers, -- intrigeri
Thomas Schmitt
2014-Jul-31 17:01 UTC
[syslinux] Workaround for "hybriding" large ISO images?
Hi,> since the Tails ISO grew from ~900MB to ~1.1GB, we see this warning > when running isohybrid on it: > > isohybrid: Warning: more than 1024 cylinders: 1045That would be the default cylinder size of 64*32*512 = 1 MiB. Try isohybrid options -h 255 -s 63 to get the maximum cylinder size of a bit less than 8 MiB. This will suffice for ISOs up to nearly 8 GiB.> So, my question is: is there a "known optimal" combination of > isohybrid options that makes the resulting hybrid'd ISO boot on as > much hardware as possible?-h 64 -s 32 is said to be the best guess for images up to 1 GiB. -h 255 -s 63 is said to be the second best one. Needed for > 1 GiB.> * I've sent a call for testing to the Tails community in order to > gather experimental results in this area, but it might be that > someone in here already knows better.It would be interesting to see how many firmwares fail resp. succeed whith above geometries in an ISO > 1 GiB. Have a nice day :) Thomas
Hi, Thomas Schmitt wrote (31 Jul 2014 17:01:19 GMT) :> -h 64 -s 32 is said to be the best guess for images up to 1 GiB. > -h 255 -s 63 is said to be the second best one. Needed for > 1 GiB.Thanks a lot! I've amended our call for testing so that people also try the latter.>> * I've sent a call for testing to the Tails community in order to >> gather experimental results in this area, but it might be that >> someone in here already knows better.> It would be interesting to see how many firmwares fail resp. > succeed whith above geometries in an ISO > 1 GiB.Sure. I'll report back here when/if I get useful test results. Cheers, -- intrigeri
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